1. Field of the Invention
This invention relates to dental impression copings of the type used in implant dentistry to take impressions of a dental implant site from which accurate models can be constructed. More particularly, the invention relates to an improved pick-up type impression coping, which utilizes a snap fit attachment coping with anti-rotational properties.
2. Description of the Related Art
Implant dentistry involves the restoration of edentulous area(s) in a patient""s mouth using artificial components, including typically an implant fixture or root and a prosthetic tooth and/or final abutment which is secured to the implant fixture. According to state of the art techniques, the process for restoring a tooth and its root is carried out generally in three stages.
Stage I involves implanting the dental implant fixture into the bone of a patient""s jaw. The oral surgeon first accesses the patient""s jawbone through the patient""s gum tissue and removes any remains of the tooth to be replaced. Next, the specific site in the patient""s jaw where the implant will be anchored is widened by drilling and/or reaming to accommodate the width of the dental implant fixture to be implanted. Then, the dental implant fixture is inserted into the hole in the jawbone, typically by screwing, although other techniques are known for introducing the implant in the jawbone.
The implant fixture itself is typically fabricated from pure titanium or a titanium alloy. Such materials are known to produce osseointegration of the fixture with the patient""s jawbone. The dental implant fixture also typically includes a hollow threaded bore through at least a portion of its body and extending out through its proximal end which is exposed through the crestal bone for receiving and supporting the final tooth prosthesis and/or various intermediate components or attachments.
After the implant is initially installed in the jawbone a temporary healing cap is secured over the exposed proximal end in order to seal the internal bore. The patient""s gums are then sutured over the implant to allow the implant site to heal and to allow desired osseointegration to occur. Complete osseointegration typically takes anywhere from four to ten months.
During stage II, the surgeon re-accesses the implant fixture by making an incision through the patient""s gum tissues. The healing cap is then removed, exposing the proximal end of the implant. A mold or impression is then taken of the patient""s mouth to accurately record the position and orientation of the implant within the mouth. This is used to create a plaster model or analogue of the mouth and/or the implant site and provides the information needed to fabricate the prosthetic replacement tooth and any required intermediate prosthetic components. Stage II is typically completed by attaching to the implant a temporary healing abutment or other transmucosal component to control the healing and growth of the patient""s gum tissue around the implant site.
Stage III involves fabrication and placement of a cosmetic tooth prosthesis to the implant fixture. The plaster analogue provides laboratory technicians with a model of the patient""s mouth, including the orientation of the implant fixture relative to the surrounding teeth. Based on this model, the technician constructs a final restoration. The final step in the restorative process is replacing the temporary healing abutment with the final restoration.
To achieve optimal results in terms of overall aesthetics and bio-functioning ability of the tooth restoration, it is essential in stage II that the plaster analogue accurately reflect the true position and orientation of the implant in the patient""s mouth and that in stage III such position and orientation is faithfully replicated when securing the final tooth restoration to the implant. To help achieve this accuracy and faithful replication, one or more indexing means are typically provided on the proximal end of the implant and corresponding mating indexing means are formed on the various mating components which are adapted to be fitted to the implant. Such indexing means provide desired orientation of the implant and mating components relative to one another and also prevent undesired rotation.
Such indexing means frequently take the form of a hexagonal boss or recess (xe2x80x9chexxe2x80x9d) formed on the proximal portion of the implant exposed through the crestal bone. For externally threaded implants the hex may also be used to engage a driving tool for driving the implant into an internally threaded bore or osteotomy prepared in the patient""s jawbone (mandible or maxilla). When the implant is fully installed in a patient""s jawbone the hex or other indexing means is typically exposed through the crestal bone so that accurate indexing may be provided between the implant and the final prosthesis and/or various intermediate mating prosthetic components.
As noted above, during stage II of the dental restorative process a mold or impression is taken of the patient""s mouth to accurately record the position(s) and orientation(s) of the indexing means within the mouth at the implant site(s) and to thereby providing the information needed to fabricate the restorative replacement(s) and/or intermediate prosthetic components. According to the state of the art, this is done using a casting or impression material formed of a soft resinxe2x80x94typically polyvinylsiloxane or polyetherxe2x80x94which can be applied over the implant site using a suitable impression tray and allowed to cure in situ. The impression material is sufficiently resilient such that it can be removed from the patient""s mouth after it is cured (or partially cured) while at the same time retaining an accurate impression of the patient""s mouth and particularly the implant site.
However, because the indexing means of the implant is typically quite small and may be recessed partially beneath the gums of a patient, a secondary or intermediate impression element is typically used to help transfer accurately the orientation of the indexing means of the implant. This intermediate impression element is commonly called a xe2x80x9ccopingxe2x80x9d or xe2x80x9cimpression coping.xe2x80x9d Examples of impression copings as found in the prior art are shown in U.S. Pat. No. 4,955,811 to Lazzara et al., e.g., FIGS. 5, 6, and 9. There are primarily two types of such impression copings used todayxe2x80x94so-called xe2x80x9ctransferxe2x80x9d impression copings and so-called xe2x80x9cpick-upxe2x80x9d impression copings. Both are conveniently adapted to be screw-retained to the implant. The choice of which technique is to use (open tray vs. closed tray) is based primarily on individual patient characteristics and the clinician""s preference.
Conventional transfer impression copings have an impression portion adapted to form a unique or indexed impression in the impression material and a base portion having mating indexing means adapted to mate with the exposed indexing means of the implant. In use, the impression coping is temporarily secured to the exposed proximal end of the implant fixture such that the mating indexing means of the impression coping and implant are interlockingly mated to one another. Typically, a threaded screw or bolt is used to temporarily secure the impression coping to the implant fixture.
Once the impression coping(s) is secured to the implant fixture(s), an impression of the coping(s) relative to the surrounding teeth is taken. A U-shaped impression tray filled with an impression material is placed in the patient""s mouth over the implant site. The patient bites down on the tray, squeezing the impression material into the implant site and around the impression coping(s). Within a few minutes, the impression material cures or hardens to a flexible, resilient consistency. The impression tray is then removed from the patient""s mouth to reveal an impression of the implant site and the impression coping(s). The restorative dentist then removes the impression coping(s) by unthreading the screw from the implant. The coping(s) is then removed from the patient""s mouth and is transferred back into the impression material, being careful to preserve the proper orientation of the indexing means. This impression method using transfer impression copings is commonly referred to as the xe2x80x9cclosed-trayxe2x80x9d technique. While the closed-tray technique is simple in its design and execution, it is sometimes prone to inaccuracies where sufficient care is not taken during the step of reinserting the impression coping(s) into the impression material.
Conventional pick-up impression copings are similar to transfer copings described above, except that pick-up impression copings typically include an embedment portion adapted to non-removably embed the impression coping securely within the impression material. Typically, the embedded portion comprises a protuberant xe2x80x9clipxe2x80x9d or similar embedment projection at their coronal aspect, such that the diameter of the lip is larger than the diameter of the immediately adjacent (more apical) area of the transfer coping. This allows for xe2x80x9cgrabbingxe2x80x9d or retention of the impression material as it is being removed from the patient""s mouth. In this case, once the impression is taken the tray is removed from the patient""s mouth, the impression coping(s) remain in the impression material and are xe2x80x9cpicked upxe2x80x9d and pulled away from the patient""s mouth along with the impression material. To facilitate such pick-up removal of conventional screw-secured impression copings, the tray is provided with one or more apertures or openings through which a tool may be inserted to loosen the screw or bolt securing each coping. Thus, this impression technique is commonly referred to as the xe2x80x9copen-trayxe2x80x9d technique. The open-tray technique is particularly well suited for multi-site dental restoration procedures, especially when there is a large divergence angle between multiple adjacent implants, or when the dentist wishes to utilize a verification stent to check the accuracy of the working stone model. The opentray technique is generally preferred for accuracy, but do to the need to cut holes or apertures in the tray, it is more complex. As a result, it often takes more time to prepare and execute.
In one embodiment the present invention provides an impression coping for taking an accurate dental impression of an implant installed in a patient""s jawbone. The impression coping has a proximal end and a distal end. The proximal end is configured and adapted to be secured to the implant and includes a protrusion that is sized and dimensioned to engage a recess formed in the implant. The coping also includes an indexing boss and/or recess formed for interlockingly engaging a corresponding mating indexing boss and/or recess formed on the implant. The distal end includes at least one annular recess, slot(s), wings, button, ball, or a criss-cross configuration for retaining the impression coping in the impression material. The coping may be configured and used as either a transfer coping or pick-up coping, as desired.
In another embodiment the present invention provides an impression coping for taking an impression of an implant installed in a patient""s mouth. The impression coping comprises a proximal end and a distal end. The proximal end is adapted to be inserted within a coronal opening formed in the implant and has anti-rotation means cooperating with corresponding anti-rotation means formed in the implant for preventing relative rotation of the coping and implant. The coping further includes resilient fingers for engaging corresponding surfaces formed within the coronal opening of the implant. The distal end of the coping includes an impression portion adapted to be embedded in a dental impression material for taking a dental impression thereof. The coping may be configured and used as either a transfer coping or pick-up coping.
In yet another embodiment the present invention provides an impression coping for recording the position and orientation of an implant installed in a patient""s jawbone. The impression coping comprises a proximal end and a distal end. The proximal end is configured with one or more resilient prongs adapted to be inserted into a coronal opening formed in the implant and to snappingly engage and secure the coping to the implant. The proximal end also includes an indexing boss or recess formed therein for interlockingly engaging a corresponding mating indexing boss or recess formed on the implant. The distal end includes an impression portion for embedding in an impression material for taking a dental impression. The coping may be configured and used as either a transfer coping or pick-up coping, as desired.
In yet another embodiment the present invention provides an impression coping for recording the position and orientation of a dental implant installed in a patient""s mouth. The impression coping includes a first end adapted to be snappingly and anti-rotationally mated to the implant and a second end including one or more blade portions adapted to be embedded in an impression material for taking a dental impression. The coping may be configured and used as either a transfer coping or pick-up coping, as desired.
In yet another embodiment the present invention provides an impression coping for recording the position and orientation of a dental implant installed in a patient""s mouth. The impression coping is snappingly and anti-rotationally mated to the implant and comprises at least one blade portion for embedment in an impression material for taking a dental impression thereof. The coping may be configured and used as either a transfer coping or pick-up coping, as desired.
In yet another embodiment the present invention provides an impression coping for recording the position and orientation of an implant installed in a patient""s jawbone. The impression coping comprises a proximal end and a distal end. The proximal end is sized and adapted to matingly and anti-rotationally engage the implant. The proximal end also has resilient fingers for snappingly mating with corresponding recesses formed within a coronal opening in the implant. The distal end comprises a generally elongated impression portion including one or more substantially flat blade portions extending radially therefrom. The coping may be configured and used as either a transfer coping or pick-up coping, as desired.
In yet another embodiment the present invention provides an impression coping for taking an impression of an implant installed in a patient""s mouth. The impression coping comprises a proximal end and a distal end. The proximal end is sized and adapted to be inserted within a coronal opening formed in the implant. The proximal end further includes anti-rotation means cooperating with corresponding anti-rotation means formed on the implant for preventing relative rotation of the coping and implant when the coping is inserted in the implant. The coping further includes resilient snap means for snappingly engaging corresponding surfaces formed within the coronal opening of the implant. The distal end of the coping includes an impression portion adapted to be embedded in a dental impression material for taking a dental impression thereof. The coping may be configured and used as either a transfer coping or pick-up coping, as desired.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.